Abstract: A wrench for dental implant is provided, including a main structure, a ratchet element and a wrench arm. The main structure has a shape of long handle, and has a trench channel along the axis of handle. The ratchet element is confined inside the main structure, with the capability to move slight along the axis of the handle, and has a protruding tooth for protruding and engaging. One end of the wrench arm is engaged to the main structure, and extends beyond to outside. The main structure includes a plurality of marks on the outer surface close to the trench channel. In this manner, the wrench arm bends to leave the trench channel during the tightening operation of dental implant, the strength of exerted force can be controlled by reading the marks of the location where the wrench arm leaves the trench channel.

Abstract: A structure for air control valve of oxygen concentrator is provided, including a main body, a side cover, an electromagnetic valve, and a linkage unit. The side cover is engaged to the side of main body, the electromagnetic valve is located on side cover, and the linkage unit is located inside main body. The inside of main body is a space, divided by separating plates to form a plurality of communicating chambers, including intake chamber, main chamber, and expel chamber. The linkage unit includes a linkage rod with two sealing pads on the outer surface for opening or sealing the chambers during airflow switching. The main chamber is only connected to either intake chamber or expel chamber at a time. The inside of side cover includes a moveable piston to provide driving force for linkage unit movement. The electromagnetic valve is on side cover to control the piston timing.